Method and apparatus for applying neuromuscular electrical stimulation

ABSTRACT

A method and apparatus for applying neuromuscular electrical stimulation to an agonist/antagonist muscle pair to move a limb about a joint includes generating a first pattern of neuromuscular electrical stimulation pulses for output through a first channel to a first pair of electrodes and generating a second pattern of neuromuscular stimulation pulses for output through a second channel to a second pair of electrodes. The first pair of electrodes are attached to the agonist muscle of the agonist/antagonist muscle pair, and the second pair of electrodes are attached to the antagonist muscle. A first pattern of electrical stimulation pulses is transmitted through the first pair of electrodes to the agonist muscle at a first intensity level to initiate contraction of the agonist muscle, and then at a second intensity level which is less than the first intensity level to continue contraction of the agonist muscle. A second pattern of electrical stimulation pulses is transmitted through the second pair of electrodes to the antagonist muscle at a first intensity level to reduce the acceleration of the limb, and then at a second intensity level which is less than the first intensity level to regulate the movement of the limb.

FIELD OF THE INVENTION

The present invention relates generally to neuromuscular electricalstimulation, and more particularly, to a method and apparatus forapplying neuromuscular electrical stimulation for inducing musclecontraction in flexing, extending, adducting or abducting a limb at ajoint.

EXPLANATION OF TECHNICAL TERMS

As used herein, the term “burst period” and similar terms refer to theperiod of time during which the neuromuscular stimulation is applied tothe muscles of the patient. As used herein, the term “rest period”,“rest interval” and similar terms refer to the period of time betweenburst periods during which the neuromuscular stimulation is not appliedto the muscles of the patient.

As used herein, the terms “frequency”, “pulse rate” and similar termsrefer to the rate at which neuromuscular electrical stimulation pulsesare delivered. The frequency is commonly expressed in hertz (Hz).

As used herein, the terms “pulse width”, “pulse duration” and similarterms refer to the duration of the positive phase of the waveform.

BACKGROUND OF THE INVENTION

Neuromuscular electrical stimulation (NMES), sometimes referred to as“functional electrical stimulation” or “FES”, is a technique by whichmuscles are induced to contract by application of electricalstimulation. NMES can be used along with exercise to strengthen anathlete's muscles, or it can be used therapeutically to strengthen andretrain muscles that have been weakened or damaged by disease ortraumatic injury. NMES can also be used when voluntary motor ability isirretrievably lost, such as may arise from various forms of paralysis,to induce contractions that provide muscle benefits similar to thatobtained by voluntary exercise. NMES may be distinguished fromtranscutaneous electrical nerve stimulation (TENS) which is used totreat pain by masking pain signals before they reach the brain.

Frequently, NMES has been applied in an attempt to activate muscles overwhich a patient has little or no conscious control. Thus, for example,U.S. Pat. No. 3,344,792 of Offner et al. describes a method andapparatus for applying NMES to the muscles of the lower leg to aid inwalking. According to this patent, one electrode is placed on the skinover the tibialis anticus muscle and another is placed on the skin overthe peroneus longus muscle. The two electrodes are then connected to aportable stimulator which is controlled by a pressure-responsive footswitch. The switch is opened when pressure is applied by the heel to theswitch, and it is closed when pressure is removed. When the switch isclosed, the stimulator unit applies brief pulses of current having aduration of 50 microseconds or less and an amplitude of 50 to severalhundred milliamperes. The voltage required is generally on the order of50-150 volts. As described in the Offner patent, the application ofelectrical stimulation in this manner not only serves as “a therapeuticmethod”, but also serves as “a substitute for the individual's ownnervous system, providing effective utilization of the individual'smuscles.”

U.S. Pat. No. 4,342,317 of Axelgaard describes a method and apparatusfor applying neuromuscular electrical stimulation to the muscles in thethorax for correction of spinal curvature deficiencies. According tothis patent, a pair of specific muscle sites within the muscle group tobe treated are selected, so that stimulation of the two muscle sites, onan alternating basis, will not result in any overlap of stimulation. Adual channel alternating stimulator is employed to generate alternatingON/OFF waveforms for each channel. The amplitude of the stimulatingpulses is within the range of 60-80 milliamperes, and the ON/OFF timesfor each of the two channels are adjusted so that one muscle groupstarts to contract while the other starts to relax, and vice-versa.

U.S. Pat. No. 4,392,496 of Stanton describes a dual-channelneuromuscular electrical stimulator which is adapted for neuromuscularstimulation at two sites for exercising muscles to prevent disuseatrophy while minimizing fatigue. The stimulator provides, on two outputchannels, alternating pulsed stimulation signals which are increased inintensity at a variable rate until a fixed intensity is reached. Thepulses are applied during an adjustable predetermined stimulation periodand removed during an adjustable predetermined resting interval. In thepreferred embodiment of the invention, the pulse rate is adjustablebetween 3 and 50 pulses per second.

U.S. Pat. No. 4,569,352 of Petrofsky et al. describes a feedback controlsystem that employs a plurality of sensors and electrodes through whichneuromuscular electrical stimulation is applied to enable standing andwalking by paraplegic and quadriplegic persons. A programmedmicroprocessor produces hip movement by generating control signals forstimulation transducers which stimulate the iliacus and hamstringmuscles. Knee flexion is produced by transducers which stimulate thequadriceps muscles, and ankle movement is produced by stimulating thegastrocnemius and tibialis muscles. The stimulation circuitry creates aseries of alternating pulses at a frequency of 50 Hz.

U.S. Pat. No. 4,586,495 of Petrofsky describes a method and apparatusfor stimulating the muscles of a patient who has suffered a spinal cordinjury during the period following the injury and prior to the time whenstimulated dynamic exercise may be commenced according to the method andapparatus of U.S. Pat. No. 4,569,352. The apparatus of the '495 patentincludes a leg brace which maintains the knee and ankle at predeterminedangles. Electrodes are applied to the muscles of the braced leg over theagonist and antagonist muscles for bending the leg about the knee andankle joints. The hamstring and quadriceps muscles function as agonistand antagonist muscles, respectively, for the knee joint and thetibialis anterior and gastrocnemius muscles function as agonist andantagonist muscles, respectively, for the ankle joint. In the preferredembodiment of the invention, the quadriceps muscles are stimulated forapproximately four seconds to cause the muscles to attempt extensionagainst the restraint of the brace. Thereafter, the quadriceps musclesare rested and the hamstring muscles are stimulated for four seconds tocause the muscles to attempt to bend the knee against the restraint ofthe brace. Then both sets of muscles are rested for four seconds, andthe sequence is repeated. After the hamstring and quadriceps muscleshave been exercised, the electrodes are placed on the tibialis anteriorand gastrocnemius muscles and a similar stimulation sequence is begunfor these muscles. A pair of load cells on the leg brace providefeedback signals to a computer which controls the application of theelectrical stimulation signals. As the muscles tire with exertion, thecomputer increases the stimulation level until a maximum value of 50volts is reached. Each stimulation signal comprises a series of pulseshaving a pulse width of about 300 microseconds and a frequency of 40pulses/second.

As mentioned above, NMES can be used along with exercise to strengthenan athlete's muscles, or it can be used therapeutically to strengthenand retrain muscles that have been weakened or damaged by disease ortraumatic injury. Thus, for example, U.S. Pat. No. 4,622,973 of Agarwaladescribes a clinical device which may be used to establish an NMESregimen, as well as a portable device which is programmable by theclinical device and which automatically reproduces the NMES regimenwhich was established in the clinical device.

U.S. Pat. No. 4,996,987 of Petrofsky describes a method and apparatusfor applying electrical stimulation to induce work-producing contractionof the muscles. According to this patent, the stimulation ofwork-producing contraction of muscles in patients with little or nonerve damage causes unacceptable pain. Consequently, the method of theinvention includes applying a high-frequency, low-amplitudedesensitizing current to the muscle to be stimulated prior to applying alow-frequency, high-amplitude stimulating current which is continuouswith the desensitizing current. The stimulating current is applied asthe desensitizing current is terminated, and the two currents arealternately applied so that no abrupt discontinuity occurs between thecurrents. Preferably, the stimulating current is a “camel-back” biphasicsignal having three segments, the first and third of which are ofopposite polarity to the second. The first and third segments aresubstantially identical in duration and magnitude, and the second has aduration equal to the sum of the durations of the first and thirdsegments and a magnitude that is equal to and of opposite polarity toeither the first or the third segment.

U.S. Pat. No. 5,562,718 of Palermo describes a device for use inapplying NMES in a series of electrical pulses in the form of sequentialpulse patterns, or dual or triple overlapping pulse patterns. Theseelectrical pulse patterns are applied through a first channel byelectrodes that are attached to the skin over an agonist muscle andthrough a second channel by electrodes that are attached to the skinover the corresponding antagonist muscle. The timing of the sequentialor overlapping pulse train patterns is reportedly selected to takeadvantage of central nervous system inhibition and facilitation byrepetitive cycling of the pulse trains to emulate reciprocating limbspeeds ranging from slow gentle arm or leg movements to the fastestrunning patterns. The commercial embodiment of the Palermo device,marketed by Accelerated Care Plus of Reno, Nev., employs electrodesapplied to the agonist and antagonist muscles to generate overlappingpulse patterns that serve to contract these muscles. According toliterature published by Accelerated Care Plus, a first pulse pattern isapplied through a first channel to the agonist muscle in a first burstperiod of approximately 75 msec., followed by a first rest interval ofabout 50 msec. and a second pulse pattern in a second burst period ofabout 50 msec. A third pulse pattern is then delivered to the antagonistmuscle through the second channel in a third burst period of about 75msec., which begins approximately 55 msec. after the beginning of thefirst burst period (of the first channel) and continues through thefirst rest interval (of the first channel) and for about 10 msec. intothe second burst period.

U.S. Pat. No. 5,980,435 of Joutras et al. describes a method andapparatus for therapeutic use of a jointed brace. According to thispatent, the brace is attached to a jointed limb and provides controlledresistance to movement of the limb about the joint. The brace may usedin conjunction with a neuromuscular stimulation device, and it may beprogrammed to resist the movement of stronger, or antagonistic, musclesagainst weaker, or agonistic, muscles. However, there is no forceapplied by the equipment to the user in the absence of an attempt tomove a limb about a joint. The force applied by the equipment is only aforce of reaction.

U.S. Pat. No. 6,845,271 of Fang et al. describes a method and apparatusfor treatment of shoulder dysfunction using neuromuscular electricalstimulation applied through intramuscular electrodes. Preferably, themethod involves asynchronous stimulation of more than one muscle group,such as a first muscle group being the supraspinatus in combination withthe middle deltoid and a second muscle group being the trapezious incombination with the posterior deltoid. This asynchronous stimulationinvolves intermittent periods of stimulation and rest, with one musclegroup being subjected to stimulation while the other is resting.

Although it is known to apply NMES to the agonist and correspondingantagonist muscles in certain pulse patterns, the inventors havedeveloped a method and apparatus for generating NMES pulses in patternsthat appear to more accurately simulate natural movement of a limb abouta joint.

SUMMARY OF THE INVENTION

The invention comprises a method and apparatus for applyingneuromuscular electrical stimulation to an agonist/antagonist musclepair to move a limb about a joint. According to this method, a device isprovided for generating a first pattern of neuromuscular electricalstimulation pulses for output through a first channel to a first pair ofelectrodes and for generating a second pattern of neuromuscularstimulation pulses for output through a second channel to a second pairof electrodes. A first pair of electrodes is provided in operativeconnection to the first channel of the device, and a second pair ofelectrodes is provided in operative connection to the second channel ofthe device. The first pair of electrodes is attached to the agonistmuscle of the agonist/antagonist muscle pair, and the second pair ofelectrodes is attached to the antagonist muscle of the muscle pair. Afirst pattern of electrical stimulation pulses is generated fortransmission through the first pair of electrodes to the agonist muscleat a first intensity level for a period sufficient to initiatecontraction of the agonist muscle, and then at a second intensity levelwhich is less than the first intensity level for a period sufficient tocontinue contraction of the agonist muscle. A second pattern ofelectrical stimulation pulses is generated for transmission through thesecond pair of electrodes to the antagonist muscle at a first intensitylevel for a period sufficient to reduce the acceleration of the limb,and then at a second intensity level which is less than the firstintensity level for a period sufficient to regulate the movement of thelimb.

In order to facilitate an understanding of the invention, the preferredembodiments of the invention are illustrated in the drawings, and adetailed description thereof follows. It is not intended, however, thatthe invention be limited to the particular embodiments described or touse in connection with the apparatus illustrated herein. Variousmodifications and alternative embodiments such as would ordinarily occurto one skilled in the art to which the invention relates are alsocontemplated and included within the scope of the invention describedand claimed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The presently preferred embodiments of the invention are illustrated inthe accompanying drawings, in which like reference numerals representlike parts throughout, and in which:

FIG. 1 is a first embodiment of a device that may be used in applyingneuromuscular electrical stimulation to an agonist/antagonist musclepair to move a limb about a joint.

FIG. 2 is a front view of a portion of the device of FIG. 1, with thefront access panel removed.

FIG. 3 is a rear view of the device of FIG. 1.

FIG. 4 is a bottom view of the device of FIG. 1.

FIG. 5 is an exploded perspective view of a second embodiment of anapparatus that may be used in applying neuromuscular electricalstimulation to an agonist/antagonist muscle pair to move a limb about ajoint.

FIG. 6 is a front view of a module which comprises a portion of theapparatus of FIG. 5.

FIG. 7 is a bottom view of the module illustrated in FIGS. 5 and 6.

FIG. 8 is a block diagram illustrating the operation of the device ofFIGS. 1-4 or the apparatus of FIGS. 5-7.

FIG. 9 is a perspective view of a patient's arm showing two pairs ofelectrodes which may be employed in the practice of a preferredembodiment of the invention.

FIG. 10 is a graphical illustration of patterns of electricalstimulation pulses which may be transmitted to an agonist muscle andcorresponding patterns of electrical stimulation pulses which may betransmitted to the associated antagonist muscle according to a preferredembodiment of the invention. The X-axis shows elapsed time and theY-axis shows the intensity of the electrical stimulation pulses.

FIG. 11 is a detailed illustration of one of the patterns of electricalstimulation pulses which may be transmitted to an agonist muscle and thecorresponding pattern of electrical stimulation pulses which may betransmitted to the associated antagonist muscle according to a preferredembodiment of the invention. The X-axis shows elapsed time and theY-axis shows the intensity of the electrical stimulation pulses.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIGS. 1-4 illustrate a preferred embodiment of a device for generatingneuromuscular electrical stimulation for inducing muscle contraction inflexing or abducting a limb at a joint. As shown therein, device 20comprises the main component of a modular system for providing thetherapeutic application of energy in multiple forms. Device 20 comprisesa combination two-channel electrotherapy and ultrasound system, whichincludes cabinet 22 having display screen 24. Device 20 also includes auser interface in the form of function keys 26 (including keys on bothsides of the display screen), which form a part of the interactiveinterface of the device. Other function keys include knob 28 whichprovides therapy “Intensity Control” and button 30, which is a therapysession “Start” key. Button 32 is a therapy session “Pause” key andbutton 34 is a therapy session “Stop” key. Front access panel 36provides access to a plurality of outlet jacks (shown in FIG. 2),including operator remote control connector 38, patient interrupt switchconnector 40, electrical stimulation outlet jack 42 (comprised ofchannel 1 connector 44 and channel 2 connector 46), microcurrent probeconnector 48 (for use when electrical stimulation is applied using amicrocurrent waveform) and ultrasound applicator connector 50. Thegenerators for the patterns of electrical stimulation pulses that areapplied according to the invention are located in device 20.

FIG. 3 shows the rear of device 20 illustrating system power switch 52and rear access panel 54, behind which is located the main power cord(not shown). FIG. 3 also shows the location of serial connector outletjack 56 for connection of a serial device (not shown) such as a handdynamometry device, an electrogoniometry device or a pressure padtransducer. FIG. 4 shows the bottom of device 20, including a firstmodule receiver which is adapted to receive several types of upgrademodules for enhancing the operation of the system. This first modulereceiver comprises ribbon cable connector 58 to which an associatedribbon cable (not shown) may be attached. The first module receiver isadapted to receive an upgrade module such as a rechargeable batterymodule, a vacuum electrode module (which is adapted to permit theapplication of electrical stimulation using vacuum electrodes instead ofadhesively applied electrodes), a module that is adapted to generateenergy in the form of electromagnetic radiation (such as an LLLT module)or other types of upgrade modules. Referring again to FIG. 4, a secondmodule receiver 60, which includes PC board contacts 62, is adapted toreceive another type of upgrade module for enhancing the operation ofdevice 20, such as an EMG module (not shown).

FIG. 5 illustrates an alternative embodiment of an apparatus forproviding neuromuscular electrical stimulation according to theinvention. As shown therein, device 120 is adapted to provideelectrotherapy and/or ultrasound therapy, but does not provide thepatterns of electrical stimulation pulses that are applied according tothe invention without upgrade module 64. Device 120 includes cabinet 122having display screen 124 and a user interface in the form of functionkeys 126 (including keys on both sides of the display screen), whichform a part of the interactive interface of the device. Other functionkeys include knob 128 which provides therapy “Intensity Control” andbutton 130, which is a therapy session “Start” key. Button 132 is atherapy session “Pause” key and button 134 is a therapy session “Stop”key. Attached to device 120 is two-channel electrical stimulationupgrade module 64 for generating the electrical stimulation pulses thatare applied through channels 1 and 2 according to the invention. Module64 (also shown in FIGS. 6 and 7) includes ribbon cable connector 66 towhich is attached one end of ribbon cable 68. The other end of ribboncable 68 is attached to a first module receiver of device 120(comprising a ribbon cable connector, not shown, but similar to ribboncable connector 58 of device 20). Device 120 also includes front accesspanel 136 which is similar to, but larger than, front access panel 36 ofdevice 20. As shown in FIG. 6, module 64 includes a plurality of outletjacks, such as operator remote control connector 70, patient interruptswitch connector 72 and electrical stimulation outlet jack 74 (comprisedof channel 1 connector 76 and channel 2 connector 78). FIG. 7illustrates a bottom view of module 64. As shown therein, it ispreferred that module 64 include secondary module receiver 80 which isessentially identical to second module receiver 60 of device 20.Secondary module receiver 80, which includes PC board contacts 82, isadapted to receive another type of upgrade module for enhancing theoperation of the system, such as an EMG module.

Referring now to FIG. 8, the operation of the embodiment of FIGS. 1-4 orthe embodiment of FIGS. 5-7 is illustrated. As shown therein,interface/main controller 90 is the control interface for the user andthe primary controller for device 20 (or device 120 and attached module64). Major components include a graphic display (such as display screen24 of device 20 or display screen 124 of device 120), displaycontroller, power supply controls, pushbuttons (including function keys26 of device 20 or function keys 126 of device 120), and a power switch(such as power switch 52 of device 20). As described above, thisinterface allows the user to select the treatment parameters desired andto control the application of neuromuscular electrical stimulationduring treatment.

Stimulation main controller 92 comprises the communication interfacebetween stimulation channel 1 controller 104, stimulation channel 2controller 106 and user interface/main controller 90. Stimulationcontroller 92 gets the treatment parameters from the user interfacecontroller 90 and passes them on to the stimulator channels. Stimulationmain controller 92 also passes operational parameters from stimulatorchannel 1 controller 104 and stimulation channel 2 controller 106 backto user interface/main controller 90.

Ultrasound controller 98 provides the communication interface betweenultrasound generator 100 and user interface/main controller 90.Ultrasound controller 98 gets the treatment parameters from userinterface controller 90 and sets up ultrasound generator 100 for properoutput through ultrasound applicator 102. The ultrasound controller alsopasses operational parameters from ultrasound generator 100 back to userinterface/main controller 90. Preferably, ultrasound generator 100produces electrical energy at a frequency of approximately 1 MHz or 3.3MHz. When connected to the ultrasound applicator it generates ultrasoundat these frequencies. Stimulation from channel 2 output circuit can berouted through the ultrasound generator and out to the ultrasoundapplicator when so desired. This is accomplished with relay switch 51and is engaged as shown in FIG. 8 (so that contact 2 is in electricalcommunication with contact 3), when the user desires apply therapeutictreatment with both electrical stimulation and ultrasoundsimultaneously.

Stimulator channel 1 controller 104 controls stimulator channel 1 outputcircuitry 94 which generates the user selected waveform, including theelectrical stimulation pulses that are applied through channel 1according to the invention. Controller 104 controls and monitors bothvoltage and current passing to the patient through channel 1, and itprovides feedback status information to stimulator main controller 92.Stimulator output circuit 94 for channel 1 is a variable high voltagepower supply capable of generating voltages of up to 500 volts andcontinuous currents as high as 250 mA. The patient is connected to theoutput circuitry through switching devices that deliver stimulationbased on the user selected waveform. The output can be controlled bymaintaining either constant current or constant voltage. The output canalso be dynamically controlled over time, varying in both amplitude andfrequency.

Stimulator channel 2 controller 106 controls stimulator channel 2 outputcircuitry 96 which generates the user selected waveform, including theelectrical stimulation pulses that are applied through channel 2according to the invention. Controller 106 controls and monitors bothvoltage and current passing to the patient through channel 2. Controller106 also provides feedback status information to stimulator maincontroller 92. Stimulator output circuit 96 for channel 2 is a variablehigh voltage power supply capable of generating voltages of up to 500volts and continuous currents as high as 250 mA. The patient isconnected to the output circuitry through switching devices that deliverstimulation based on the user selected waveform. Like the output fromchannel 1, the output from channel 2 can be controlled by maintainingeither constant current or constant voltage. The output can also bedynamically controlled over time, varying in both amplitude andfrequency. The positive (+) output connection from channel 2 can berouted through ultrasound generator 100 to the ultrasound applicatorwhen this mode of operation is selected by use of switch S1 so thatcontact 2 is in electrical communication with contact 1 (not shown).

The invention comprises a method and apparatus for applyingneuromuscular electrical stimulation to an agonist/antagonist musclepair to move a limb about a joint. Such agonist/antagonist muscle pairsmay include (among others) the biceps and triceps for moving the forearmabout the elbow joint, finger flexors and finger extensors for movingthe fingers about various finger joints, the wrist flexors and wristextensors for moving the hand about the wrist joint, the quadricep andhamstring for moving the lower leg about the knee joint and the anteriortibialis and gastroc/soleus for moving the foot about the ankle joint.According to the method of the invention, a device, such as device 20 orthe device 120/module 64 combination, is provided for generating a firstpattern of neuromuscular electrical stimulation pulses for outputthrough a first channel to a first pair of electrodes and a secondpattern of neuromuscular stimulation pulses for output through a secondchannel to a second pair of electrodes. FIG. 9 illustrates theapplication of electrode 108 and electrode 109 from channel 1 to theskin over the wrist and finger flexor muscles (the agonist) of theforearm, although the relative positions of the electrodes of channel 1may be reversed, or the electrodes may be placed in different positions.Electrode 108 is operatively attached to channel 1 output circuit 94(shown in FIG. 8) by electrode lead 110, and electrode 109 isoperatively attached to channel 1 output circuit 94 by electrode lead111. Similarly, electrode 112 and electrode 113 from channel 2 areapplied to the skin over the wrist and finger extensor muscles (theantagonist) of the forearm, although the relative positions of theelectrodes of channel 2 may be reversed, or the electrodes may be placedin different positions. Electrode 112 is operatively attached to channel2 output circuit 96 (shown in FIG. 8) by electrode lead 114, andelectrode 113 is operatively attached to channel 2 output circuit 96 byelectrode lead 115. The electrodes from each channel are preferablyplaced no further apart than the length (or diameter) of the smallestelectrode. Preferably, the electrode pairs should be positionedlongitudinally with respect to the direction of the muscle fibers. Theelectrodes of channel 1 are preferably placed on either end of themuscle bellies of the agonist muscle (or muscle group) and theelectrodes of channel 2 are preferably placed on either end of themuscle bellies of the corresponding antagonist muscle (or muscle group).

When the first pair of electrodes 108 and 109 are properly attached tomake electrical contact with the agonist muscles of the patient and toconduct neuromuscular electrical stimulation pulses from channel 1output circuit 94 of device 20 (or the combination of device 120 andmodule 64), and the second pair of electrodes 112 and 113 are properlyattached to make electrical contact with the antagonist muscles of thepatient and to conduct neuromuscular electrical stimulation pulses fromchannel 2 output circuit 96, a first pattern 140 of electricalstimulation pulses (shown in FIGS. 10 and 11) are generated fortransmission through the first pair of electrodes to the agonist muscle,and a second pattern 142 of electrical stimulation pulses are generatedfor transmission through the second pair of electrodes to the antagonistmuscle. Preferably, the first pattern of electrical stimulationcomprises a series of pulses, each of which has a pulse duration withinthe range of 20-400 μsec., most preferably within the range of 100-400μsec. It is also preferred that the second pattern of electricalstimulation comprises a series of pulses, each of which has a pulseduration within the range of 20-400 μsec., and most preferably withinthe range of 100-400 μsec. Further, it is preferred that the firstpattern 140 of electrical stimulation pulses be generated during aplurality of first burst periods 148, each of which has a durationwithin the range of 200-5000 msec., and that each first burst period befollowed by a rest period or rest interval during which no electricalstimulation pulses are generated for transmission through the firstchannel. Preferably, each first burst period 148 is followed by a restperiod 150 which has a duration at least 2-5 times the duration of thepreceding first burst period. Similarly, it is preferred that the secondpattern 142 of electrical stimulation pulses be generated during aplurality of second burst periods 152, each of which begins after thebeginning of a first burst period and ends no later than (and mostpreferably simultaneously with) the end of the first burst period. It isalso preferred that each of second burst periods 152 has a durationwithin the range of 200-5000 msec., and that each second burst period isfollowed by a rest period or rest interval during which no electricalstimulation pulses are generated for transmission through the secondchannel. Preferably, each second burst period 152 is followed by a restperiod 154 which has a duration at least 2-5 times the duration of thepreceding second burst period.

It is also preferred that the first pattern of electrical stimulationpulses be generated or provided in a waveform selected from the groupconsisting of symmetrical biphasic, asymmetrical biphasic, high volt andpremodulated (most preferably symmetrical biphasic), and that the secondpattern of electrical stimulation pulses be generated or provided in awaveform selected from the group consisting of symmetrical biphasic,asymmetrical biphasic, high volt and premodulated (most preferablysymmetrical biphasic). Furthermore, it is preferred that first pulsepattern generating circuit 94 be adapted to generate a first pattern ofelectrical stimulation pulses having a frequency 144 within the range of20-80 Hz and an intensity (or intensities) within the range of 10-150mA., and that second pulse pattern generating circuit 96 be adapted togenerate a second pattern of electrical stimulation pulses having afrequency 146 within the range of 20-80 Hz and an intensity (orintensities) within the range of 10-150 mA.

As shown in FIG. 11, preferred first pulse pattern generating circuit 94is adapted to generate a first pattern of electrical stimulation pulsesfor transmission through a first pair of electrodes 108 and 109 to theagonist muscle at a first intensity level 156 for a period 158 which issufficient to initiate contraction of the agonist muscle, and at asecond intensity level 160 which is less than the first intensity level(and most preferably 75-90% of the first intensity level) for a period162 that is sufficient to continue contraction of the agonist muscle,and at a third intensity level which is greater than the secondintensity level (and most preferably equal to the first intensity level156) for a period 164 that is sufficient to complete contraction of theagonist muscle. It is also contemplated within the scope of theinvention that the first pattern of electrical stimulation pulses may betransmitted at a first intensity level 156 for a period 158 which issufficient to initiate contraction of the agonist muscle, and at asomewhat lower intermediate intensity level 166 (preferably about 85% ofthe first intensity level) for a period 168, and at a second intensitylevel 160 which is less than the first intensity level (preferably about80% of the first intensity level) for a period 162 that is sufficient tocontinue contraction of the agonist muscle, and finally at a thirdintensity level which is greater than the second intensity level (andpreferably equal to the first intensity level 156) for a period 164 thatis sufficient to complete contraction of the agonist muscle. Preferredfirst pulse pattern generating circuit 94 is also adapted to generate afirst pattern of electrical stimulation pulses having period 162 of thesecond intensity level that is at least three times greater than period158 of the first intensity level, and a period 164 of the thirdintensity level that is not greater than period 158 of the firstintensity level.

Preferred second pulse pattern generating circuit 96 is adapted togenerate a second pattern of electrical stimulation pulses fortransmission through a second pair of electrodes 112 and 113 to theantagonist muscle, at a first intensity level 170 for a period 172 thatis sufficient to reduce the acceleration of the limb, and at a secondintensity level 174 which is less than the first intensity level (andmost preferably 10-30% of the first intensity level) for a period 176that is sufficient to regulate the movement of the limb, and at a thirdintensity level which is greater than the second intensity level (andpreferably equal to first intensity level 170) for a period 178 that issufficient to stop the movement of the limb. Preferred second pulsepattern generating circuit 96 is also adapted to generate a secondpattern of electrical stimulation pulses having a period 176 of thesecond intensity level that is 5-15 times greater than period 172 of thefirst intensity level and not more than five times greater than theperiod of the third intensity level, and having a period 178 of thethird intensity level that is not more than three times greater thanperiod 172 of the first intensity level.

Although this description contains many specifics, these should not beconstrued as limiting the scope of the invention but as merely providingillustrations of some of the presently preferred embodiments thereof, aswell as the best mode contemplated by the inventor of carrying out theinvention. The invention, as described herein, is susceptible to variousmodifications and adaptations, and the same are intended to becomprehended within the meaning and range of equivalents of the appendedclaims.

What is claimed is:
 1. A method for applying neuromuscular electricalstimulation to an agonist/antagonist muscle pair to move a limb about ajoint, which method comprises: providing a device for generating a firstpattern of neuromuscular electrical stimulation pulses for outputthrough a first channel to a first pair of electrodes attached to anagonist muscle of an agonist/antagonist muscle pair and a second patternof neuromuscular stimulation pulses, different from the first pattern,for output through a second channel to a second pair of electrodesattached to an antagonist muscle of the agonist/antagonist muscle pair;automatically generating, for each burst period of a plurality of burstperiods, the first pattern of electrical stimulation pulses fortransmission through the first pair of electrodes to the agonist muscle:(i) at a constant first current amplitude level for a period sufficientto initiate contraction of the agonist muscle; (ii) consecutive to theperiod of the first current amplitude level, at a constant secondcurrent amplitude level less than the first current amplitude level fora period sufficient to continue contraction of the agonist muscle;automatically generating, for each burst period of the plurality ofburst periods, the second pattern of electrical stimulation pulses fortransmission through the second pair of electrodes to the antagonistmuscle: (i) at a constant third current amplitude level for a periodsufficient to reduce the acceleration of the limb; (ii) consecutive tothe period of the third current amplitude level, at a constant fourthcurrent amplitude level less than the third current amplitude level fora period sufficient to regulate the movement of the limb; wherein eachburst period of the plurality of burst periods: (i) represents apredetermined period of time during which electrical stimulation isapplied to the agonist/antagonist muscle pair, and (ii) is followed by apredetermined rest period during which electrical stimulation is notapplied to the agonist/antagonist muscle pair.
 2. The method of claim 1wherein: the second current amplitude level is 75-90% of the firstcurrent amplitude level; and the fourth current amplitude level is10-30% of the third current amplitude level.
 3. The method of claim 1wherein: the period of the second current amplitude level is at leastthree times greater than the period of the first current amplitudelevel; and the period of the fourth current amplitude level is 5-15times greater than the period of the third current amplitude level. 4.The method of claim 1 wherein: the first pattern of electricalstimulation pulses comprises a series of pulses, each of which has apulse duration that is within the range of 20-400 μsec; and the secondpattern of electrical stimulation pulses comprises a series of pulses,each of which has a pulse duration that is within the range of 20-400μsec.
 5. The method of claim 1 wherein: the first pattern of electricalstimulation pulses comprises a series of pulses generated at a frequencythat is within the range of 20-80 Hz; and the second pattern ofelectrical stimulation pulses comprises a series of pulses generated ata frequency that is within the range of 20-80 Hz.
 6. The method of claim1 wherein: the electrical stimulation pulses in the first pattern ofelectrical stimulation pulses are generated at current amplitudes withinthe range of 10-150 mA; and the electrical stimulation pulses in thesecond pattern of electrical stimulation pulses are generated at currentamplitudes within the range of 10-150 mA.
 7. The method of claim 1wherein: the first pattern of electrical stimulation pulses comprises awaveform selected from the group consisting of symmetrical biphasic,asymmetrical biphasic, high volt and premodulated; and the secondpattern of electrical stimulation pulses comprises a waveform selectedfrom the group consisting of symmetrical biphasic, asymmetricalbiphasic, high volt and premodulated.
 8. The method of claim 1 whereineach burst period of the plurality of burst periods has a durationwithin the range of 200-5000 msec.
 9. The method of claim 1 wherein eachburst period is followed by a predetermined rest period during whichelectrical stimulation is not applied to the agonist/antagonist musclepair, and each rest period has a duration at least 2-5 times theduration of the immediately preceding burst period.
 10. A method forapplying neuromuscular electrical stimulation to an agonist/antagonistmuscle pair to move a limb about a joint, which method comprises:providing a device for generating a first pattern of neuromuscularelectrical stimulation pulses for output through a first channel to afirst pair of electrodes attached to an agonist muscle of anagonist/antagonist muscle pair and a second pattern of neuromuscularstimulation pulses, different from the first pattern, for output througha second channel to a second pair of electrodes attached to anantagonist muscle of the agonist/antagonist muscle pair; automaticallygenerating, for each burst period of a plurality of burst periods, afirst pattern of electrical stimulation pulses for transmission throughthe first pair of electrodes to the agonist muscle: (i) at a constantfirst intensity level for a period sufficient to initiate contraction ofthe agonist muscle; (ii) consecutive to the period of the firstintensity level, at a constant second intensity level, less than thefirst intensity level, for a period sufficient to continue contractionof the agonist muscle, the second intensity level period consecutive tothe first intensity level period; (iii) consecutive to the period of thesecond intensity level, at a constant third intensity level, greaterthan the second intensity level, for a period sufficient to completecontraction of the agonist muscle, the third intensity level periodconsecutive to the second intensity level period; automaticallygenerating, for each burst period of the plurality of burst periods, asecond pattern of electrical stimulation pulses for transmission throughthe second pair of electrodes to the antagonist muscle: (i) at aconstant fourth intensity level for a period sufficient to reduce theacceleration of the limb; (ii) consecutive to the period of the fourthintensity level, at a constant fifth intensity level, less than thefourth intensity level, for a period sufficient to regulate the movementof the limb, the fifth intensity level period consecutive to the fourthintensity level period; (iii) consecutive to the period of the fifthintensity level, at a constant sixth intensity level, greater than thefifth intensity level for a period sufficient to stop the movement ofthe limb, the sixth intensity level period consecutive to the fifthintensity level period; wherein each burst period of the plurality ofburst periods: (i) represents a predetermined period of time duringwhich electrical stimulation is applied to the agonist/antagonist musclepair; and (ii) includes generating the first pattern of electricalstimulation pulses during a first burst period and generating the secondpattern of electrical stimulation pulses during a second burst periodthat begins after the beginning of the first burst period and ends nolater than the end of the first burst period.
 11. The method of claim 10wherein the second burst period ends at the same time that the firstburst period ends.
 12. The method of claim 10 wherein: the secondintensity level is 75-90% of the first intensity level; the thirdintensity level is approximately equal to the first intensity level; thefifth intensity level is 10-30% of the fourth intensity level; and thesixth intensity level is approximately equal to the fourth intensitylevel.
 13. The method of claim 10 wherein: the period of the secondintensity level of the first pattern of electrical stimulation pulses isat least three times greater than the period of the first intensitylevel of the first pattern of electrical stimulation pulses; the periodof the third intensity level of the first pattern of electricalstimulation pulses is not greater than the period of the first intensitylevel of the first pattern of electrical stimulation pulses; and theperiod of the fifth intensity level of the second pattern of electricalstimulation pulses is 5-15 times greater than the period of the fourthintensity level of the second pattern of electrical stimulation pulses;and the period of the sixth intensity level of the second pattern ofelectrical stimulation pulses is not more than three times greater thanthe period of the fourth intensity level of the second pattern ofelectrical stimulation pulses.
 14. The method of claim 10 wherein: thesecond intensity level of the first pattern of electrical stimulationpulses includes a first phase which has an intensity level about 85% ofthe first intensity level for a period that is no shorter than theperiod of the first intensity level, and a second phase which has anintensity level about 80% of the first intensity level for a periodsufficient to continue contraction of the agonist muscle.
 15. A devicefor applying neuromuscular electrical stimulation to anagonist/antagonist muscle pair to move a limb about a joint, said devicecomprising a main simulator controller and a pulse pattern generatingcircuitry in communication with the main stimulator controller, whereinthe main stimulator controller is configured to control said pulsepattern generating circuitry to: automatically generate, for each burstperiod of a plurality of burst periods, a first pattern of electricalstimulation pulses for transmission through a first pair of electrodesto the agonist muscle: (i) at a constant first intensity level for aperiod sufficient to initiate contraction of the agonist muscle; (ii) ata constant second intensity level, less than the first intensity level,for a period sufficient to continue contraction of the agonist muscle,the second intensity level period consecutive to the first intensitylevel period; (iii) at a constant third intensity level, greater thanthe second intensity level, for a period sufficient to completecontraction of the agonist muscle, the third intensity level periodconsecutive to the second intensity level period; automaticallygenerate, for each burst period of the plurality of burst periods, asecond pattern of electrical stimulation pulses, different from thefirst pattern, for transmission through the second pair of electrodes tothe antagonist muscle: (i) at a constant fourth intensity level for aperiod sufficient to reduce the acceleration of the limb; (ii) at aconstant fifth intensity level, less than the fourth intensity level,for a period sufficient to regulate the movement of the limb, the fifthintensity level period consecutive to the fourth intensity level period;(iii) at a constant sixth intensity level, greater than the fifthintensity level, for a period sufficient to stop the movement of thelimb, the sixth intensity level period consecutive to the fifthintensity level period; wherein each burst period of the plurality ofburst periods: (i) represents a predetermined period of time duringwhich electrical stimulation is applied to the agonist/antagonist musclepair, and (ii) includes generating the first pattern of electricalstimulation pulses during a first burst period and generating the secondpattern of electrical stimulation pulses during a second burst periodthat begins after the beginning of the first burst period and ends nolater than the end of the first burst period.
 16. The device of claim 15wherein: the second intensity level is 75-90% of the first intensitylevel; and the fifth intensity level is 10-30% of the fourth intensitylevel.
 17. The device of claim 15 wherein: the period of the secondintensity level is at least three times greater than the period of thefirst intensity level; and the period of the fifth intensity level is5-15 times greater than the period of the fourth intensity level. 18.The device of claim 15 wherein: the first pattern of electricalstimulation pulses comprises a series of pulses, each of which has apulse duration within the range of 20-400 μsec; and the second patternof electrical stimulation pulses comprises a series of pulses, each ofwhich has a pulse duration within the range of 20-400 μsec.
 19. Thedevice of claim 15 wherein: the a first pattern of electricalstimulation pulses comprises a series of pulses generated at a frequencywithin the range of 20-80 Hz; and the second pattern of electricalstimulation pulses comprises a series of pulses generated at a frequencywithin the range of 20-80 Hz.
 20. The device of claim 15 wherein: theelectrical stimulation pulses in the first pattern are generated atcurrent amplitudes within the range of 10-150 mA; and the electricalstimulation pulses in the second pattern are generated at currentamplitudes within the range of 10-150 mA.
 21. The device of claim 15wherein: the first pattern of electrical stimulation pulses comprises awaveform selected from the group consisting of symmetrical biphasic,asymmetrical biphasic, high volt and premodulated; and the secondpattern of electrical stimulation pulses comprises a waveform selectedfrom the group consisting of symmetrical biphasic, asymmetricalbiphasic, high volt and premodulated.
 22. The device of claim 15wherein: the second pattern of electrical stimulation pulses isgenerated during a second burst period that begins after the beginningof the first burst period and ends at the same time that the first burstperiod ends.
 23. The device of claim 15 wherein: the second intensitylevel is 75-90% of the first intensity level; the third intensity levelis approximately equal to the first intensity level; the fifth intensitylevel is 10-30% of the fourth intensity level; and the sixth intensitylevel is approximately equal to the fourth intensity level.
 24. Thedevice of claim 15 wherein: the period of the second intensity level isat least three times greater than the period of the first intensitylevel; the period of the third intensity level is not greater than theperiod of the first intensity level; the period of the fifth intensitylevel is 5-15 times greater than the period of the fourth intensitylevel; and the period of the sixth intensity level is not more thanthree times greater than the period of the fourth intensity level. 25.The device of claim 15 wherein each burst period of the plurality ofburst periods has a duration within the range of 200-5000 msec.
 26. Thedevice of claim 15 wherein each burst period is followed by apredetermined rest period during which electrical stimulation is notapplied to the agonist/antagonist muscle pair, and each rest period hasa duration at least 2-5 times the duration of the immediately precedingburst period.